Modern cars comprise electronic control systems or vehicle handling systems like traction control system (TCS), Electronic Stability Program (ESP), active suspension system or Anti-lock braking system (ABS). Besides these active control systems there also exist vehicle driver safety information systems such as road friction indicators and sensor-free tire pressure monitoring system, e.g. indirect tire pressure monitoring system (iTPMS), which present information about the driving condition to the driver.
All the above-mentioned systems benefit from the knowledge about a large set of estimated or measured vehicle properties parameters such as tire air pressure, tire longitudinal stiffness, ambient temperature, tire temperature, wheel resonance frequency, carried vehicle load, tire radius change while cornering and wheel vibration dependent on speed.
Knowledge about actual road surface conditions (also referred to as quality of a road) is of interest. Road surface condition information, e.g., about certain road sections can be useful for, e.g., authorities such as the department of transportation for maintenance purposes, travelers who want to plan their route and find the most comfortable way to get from point A to point B.
For example, on the basis of road surface condition information it is possible to detect road surface anomalies that, when left unreported, can cause wear of vehicles, lesser driving comfort and vehicle controllability, or an accident.
Also, knowledge on road surface conditions can be used for electronic control systems of vehicles. Modern vehicles comprise electronic control systems like anti-lock-braking systems (ABS), dynamic stability systems, anti-spin systems and traction control systems. Besides these active control systems there also exist driver safety information systems such as road friction indicators and sensor-free tire pressure monitoring systems which present information about the driving condition to the driver. Such systems may benefit from knowledge about road surface conditions under the vehicle in order to take into account the current actual surface condition of a road a vehicle is presently moving (or will do so) to optimize system performance (e.g. adapt brake forces and/or intervals). For example, in vehicles with an active damping system, information on the road surface condition can be used to pre-set/adjust the stiffness of the suspension. In this way travelling over short segments of the road considered as rough by the driver, gravel road, potholes, speed bumps, “sleeping policemen” or the like can be made more comfortable for the driver/passengers and less damage can be caused to the vehicle in question.
Known approaches to obtain information on road surface conditions utilize smartphone-based applications employing GPS information, images taken by vehicle-mounted cameras and laser sensor scanning the road surface. Such approaches require additional components that normally are not part of a vehicle.